Valve assembly for introducing instruments into body cavities

ABSTRACT

A valve assembly adapted for introduction of surgical instruments into a patient&#39;s body includes a valve body formed of a flexibly resilient material which defines an aperture for reception of the instrument. The aperture is configured and dimensioned such that insertion of the instrument into the aperture will cause the resilient material of the valve body to resiliently engage the outer surface of the instrument in a substantially gas tight manner. The valve assembly includes a biasing member for closing the valve body to form a gas tight seal prior to inserting the instrument therethrough.

This is a divisional of U.S. application Ser. No. 08/167,230 filed Dec.14, 1993 now U.S. Pat. No. 5,360,417, which is a continuation of U.S.application Ser. No. 07/874,291 filed Apr. 24, 1992 now abandoned.

BACKGROUND OF THE INVENTION

1. Field of the Invention

This invention relates to valve systems of the type adapted to allow theintroduction of a surgical instrument into a patient's body, Inparticular, the invention is applicable to a cannula assembly wherein acannula extends from the valve assembly and is intended for insertioninto a patient's body to accommodate an instrument inserted through thecannula and valve.

2. Background of the Prior Art

In laparoscopic procedures surgery is performed in the interior of theabdomen through a small incision; in endoscopic procedures surgery isperformed in any hollow viscus of the body through narrow tubes orcannula inserted through a small entrance incision in the skin.Laparoscopic and endoscopic procedures generally require that anyinstrumentation inserted into the body be sealed, i.e. provisions mustbe made to ensure that gases do not enter or exit the body through theincision as, for example, in surgical procedures in which the surgicalregion is insufflated. Moreover, laparoscopic and endoscopic proceduresoften require the surgeon to act on organs, tissues, and vessels farremoved from the incision, thereby requiring that any instruments usedin such procedures be relatively long and narrow.

For such procedures, the introduction of a tube into certain anatomicalcavities such as the abdominal cavity is usually accomplished by use ofa trocar assembly comprised of a cannula assembly and an obturator. Thecannula assembly includes a cannula tube attached to a valve assemblywhich is adapted to maintain a seal across the opening of the cannulaassembly. Since the cannula tube is in direct communication with theinternal portion of the valve assembly, insertion of the cannula tubeinto an opening in the patient's body so as to reach the inner abdominalcavity must maintain a relatively gas-tight interface between theabdominal cavity and the outside atmosphere.

Since surgical procedures in the abdominal cavity of the body requireinsufflating gases to raise the cavity wall away from vital organs, theprocedure is usually initiated by use of a Verres needle through which agas such as CO₂ is introduced into the body cavity. Thereafter, thepointed obturator of the trocar assembly is inserted into the cannulaassembly and used to puncture the abdominal cavity wall. The gasprovides a slight pressure which raises the inner wall surface away fromthe vital organs thereby avoiding unnecessary contact with the organs bythe instruments inserted into the cannula. Following removal of theobturator, laparoscopic or endoscopic surgical instruments may then beinserted through the cannula assembly to perform surgery within theabdominal cavity.

In view of the need to prevent leakage of the insufflation gas from thecavity, the cannula is typically provided with a valve assembly whichpermits introduction of surgical instruments to provide selectivecommunication between the inner atmosphere of the cavity with theoutside atmosphere. In this regard, there have been a number of attemptsin the prior art to provide such a seal as part of the cannula assembly.

One form of cannula assembly includes a flapper valve which is pivotallymounted within the cannula assembly and is automatically opened by theobturator or other object when it is inserted into the proximal end ofthe cannula. Conventional flapper valves may also be manually opened bypivoting a lever on the exterior of the cannula housing. See, e.g., U.S.Pat. No. 4,943,280 to Lander. Trumpet valves are also known.

U.S. Pat. No. 4,655,752 to Honkanen et al. discloses a cannula includinga housing and first and second seal members. The first seal member isconically tapered towards the bottom of the housing and has a circularopening in its center, while the second seal member is cup-shaped andalso possesses a conically tapered bottom end. The second seal memberincludes at least one slit in the center of the conically tapered bottomend to allow for passage of instruments.

U.S. Pat. No. 4,978,341 to Niederhauser discloses an introducer valvefor a catheter in which an elastomeric valve body is provided with acentral longitudinal opening. The valve body has an inner wall taperinginwardly to a central opening, and an outer wall which also tapersinwardly generally parallel with the inner wall. A ring may circumscribethe center of the valve body to bias the central opening into a closedposition.

Although attempts have been made to provide a valve assembly whichmaintains the integrity of the seal between the body cavity and theatmosphere outside the patient's body, seal systems provided to datehave failed to address the full range of surgeons' needs, especiallywhen instruments varying in diameter are used.

The present invention provides a valve assembly which may beincorporated into a cannula assembly or utilized in combination with anytype of tubular member for introduction into the body of a patient whilepermitting introduction of instruments through the valve assembly intothe body. At all times, the surgeon maintains control over the interfacebetween the atmospheres within and without the patient's body. Moreover,the present invention makes it possible to introduce instruments ofvarying sizes into the body and insures the maintenance of a gas sealdespite instrument manipulation therethrough.

SUMMARY OF THE INVENTION

A valve assembly is provided for permitting introduction of an elongatedobject, typically of circular cross-section, such as a surgicalinstrument into a patient's body through a tube such as a cannula. Thevalve assembly includes a valve body formed of a flexibly resilientmaterial which defines an aperture for reception of the object. Theaperture is configured and dimensioned such that insertion of the objectinto the aperture will cause the flexible material defining the apertureto resiliently engage the outer surface of the object in a substantiallygas tight manner. The valve assembly may further include a member forbiasing the flexible material to a configuration whereby the aperture isnormally closed to form a gas tight seal prior to inserting the objecttherethrough.

BRIEF DESCRIPTION OF THE DRAWINGS

The forgoing features of the present invention will become more readilyapparent and will be understood by referring to the following detaileddescription of preferred embodiments of the invention, which aredescribed hereinbelow with reference to the drawings wherein:

FIG. 1 is a perspective view illustrating a valve assembly according tothe present invention;

FIG. 2 is a side elevational view illustrating the valve assembly ofFIG. 1;

FIG. 3 is a cross-sectional view along line 3--3 of FIG. 2;

FIG. 4 is a perspective view illustrating an assembly step of the valveassembly of FIG. 1;

FIG. 5 is a perspective partial cut-away view illustrating introductionof fluid into the valve assembly to provide compressive biasing of thevalve;

FIG. 6 is a side elevational partial cut-away view illustrating thevalve assembly prior to insertion of a surgical instrument;

FIG. 7 is a side elevational partial cut-away view illustrating thevalve assembly during insertion of a surgical instrument;

FIG. 8 is a side elevational partial cut-away view illustrating thevalve assembly with a surgical instrument fully inserted;

FIG. 9 is a side elevational partial cut-away view illustrating thevalve assembly during removal of a surgical instrument;

FIG. 10 is a side elevational partial cut-away view illustrating anotherembodiment of a valve assembly according to the present invention;

FIG. 11 is a perspective view illustrating another embodiment of a valveassembly according to the present invention;

FIG. 12 is a side elevational partial cut-away view illustrating thevalve assembly with an instrument fully inserted;

FIG. 13 is a side elevational partial cut-away view illustrating thevalve assembly during withdrawal of the instrument;

FIG. 14 is a side elevational partial cut-away view illustrating anotherembodiment of the valve assembly according to the present invention;

FIG. 15 is a side elevational partial cut-away view illustrating thevalve assembly showing the clearance afforded an instrument at a distalend of the valve assembly;

FIG. 16 is a side elevational partial cut-away view illustrating anotherembodiment of the valve assembly according to the present invention;

FIG. 17 is a cross-sectional view along line 17--17 of FIG. 8;

FIG. 18 is an enlarged cross-sectional view as shown in FIG. 17illustrating a ridge used in accordance with the invention;

FIG. 19 is a cross-sectional view along line 19--19 of FIG. 18;

FIG. 20 is an exploded perspective view of a cannula of a trocarassembly illustrating the valve assembly in partial cut-away;

FIG. 21 is a cross-sectional view of a fully assembled cannula takenalong lines 21--21 of FIG. 20 illustrating the valve assembly accordingto the present invention;

FIG. 22 is a perspective view in partial cut-away of another embodimentof the cannula of FIG. 20 illustrating the valve assembly according tothe present invention;

FIG. 23 is a perspective view in partial cut-away of the cannula of FIG.22 illustrating another embodiment of the biasing means for the valveassembly;

FIG. 24 is a perspective view in partial cut-away of the cannula of FIG.22 illustrating another embodiment of the biasing means for the valveassembly;

FIG. 25 is a perspective view in partial cut-away of the cannula of FIG.22 illustrating another embodiment of the biasing means for the valveassembly;

FIG. 26 is a top view in partial cut-away of the cannula of FIG. 22illustrating another embodiment of the biasing means for the valveassembly; and

FIG. 27 is a top view of a cam used in accordance with the embodiment ofFIG. 26.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

The present invention contemplates introduction into a patient's body ofall types of surgical instruments including, but not limited to clipappliers, lasers, photographic devices, graspers, scissors, tubes, andthe like. All of such objects are referred to herein as "instruments".

Referring now in detail to the drawings, in which like referencenumerals identify identical or similar elements, FIGS. 1-5 illustrate avalve assembly 10 which includes body 12 fabricated from a flexiblyresilient material, e.g., a thermoplastic elastomeric polymer such asKraton D, a styrene-butadiene elastomer available from Shell ChemicalCo.. The body 12 defines a substantially central longitudinal aperture14 which is designed and configured to receive an endoscopic portion ofan instrument. The body 12 further includes a proximal end portion 16,and a distal end portion 18 which is elongated and substantiallycylindrical in shape. The distal end portion 18 further includes adistal edge 20 whose significance will be discussed below. The proximalend portion 16 includes an opening 22, a wall plate 24, and an inwardlytapered neck portion 26. The body 12 further includes a middle portion28 having substantially cylindrical walls. The axial length of middleportion 28 is typically from about 5 mm to about 4 cm, and preferablyabout 1.5 to 3 cm.

Referring to FIG. 3, the proximal end portion 16 further includes aplurality of splines 32 attached to an inner wall 34 and preferablyintegrally molded as part of inner wall 34. Alternatively, splines 32may be insert molded and may include rigid members below the surface ofinner wall 34, e.g., metallic strips or the like. The splines 32 extendin a generally longitudinal direction to assist in the insertion of aninstrument into the neck portion 26 by reducing friction and drag forcesassociated therewith. Further, the splines 32 substantially preventunwanted contact between the instrument and the inner wall 34 of theneck 26 that may injure or puncture the body 12. The distal portion 18of the body 12 includes an inlet port 36 and an outlet port 38 whosefunction will be described below.

As shown in FIGS. 4 and 5, the elongated substantially cylindricaldistal portion 18 is folded onto itself and pulled proximally in thedirection of the arrows. The distal edge 20 is affixed to the proximalwall plate 24 creating a cavity 40 by conventional techniques such asadhesives or heat sealing. Inlet port 36 is provided for injection of agel 42, e.g., silicone, or like substance into cavity 40 while outletport 38 provides a conduit for eliminating air from cavity 40. The gel42 fills cavity 40 and provides longitudinal and radial pressure aboutthe aperture 14. The gel 42 biases the middle portion 28 of aperture 14closed, preventing gases and fluids from escaping through the body 12when no instrument is present in the valve assembly 10. Similarly, thegel 42 biases the middle portion 28 of aperture 14 into fluid tightcontact when an instrument is present in the aperture by longitudinallyand radially providing pressure about the aperture 14. Valve assembly 10is preferably incorporated into a cannula assembly of a trocar assemblysimilar to specific embodiments described herein below.

Aperture 14 is typically dimensioned less than or equal to the diameterof any instrument intended for entry into the proximal end of the body12. Preferably, valve assembly 10 is fabricated from a material which issufficiently flexible and resilient to accommodate and provide a sealabout instruments of varying diameters, e.g., diameters of from 3 mm to15 mm, and preferable diameters of from 5 mm to 12 mm.

Referring to FIGS. 6-9, a pointed obturator is shown approaching andentering valve assembly 10; however, any elongated relatively narrowinstrument is contemplated. The valve assembly 10 accommodates theendoscopic portion of an instrument 44. The splines 32 engage theinstrument 44 and protect the valve inner wall 34 at neck portion 26while providing for the instrument's smooth entry into aperture 14. Themiddle portion 28 of the body portion 12 surrounds the instrument andprovides longitudinal and radial pressure which substantially preventsgases or fluids from escaping from the body cavity when the instrumentis inserted. The proximal opening 22 is of such a diameter to sealinglyengage instrument 44 during insertion and withdrawal.

Another embodiment of the valve assembly 10 is shown in FIG. 10. Thevalve assembly 10a is similar to the previous embodiment shown in FIGS.1-9, however, the embodiment shown in FIG. 10 includes a plurality ofnubs 46, and the splines have been eliminated. The nubs 46 arepositioned in the inner wall 34 of the neck portion 26 and extendoutwardly from the inner wall 34. The nubs 46 engage the instrumentduring insertion of the instrument and minimize the risk of damage tothe elastomeric inner wall, e.g., puncture thereof, by providing anintermediate surface between the instrument and the inner wall 34. Thenubs are fabricated of the same elastic material as the valve assembly10a and molded integrally with the valve body. The nubs 46 may also befabricated of a different suitable flexible material.

Another embodiment of the valve assembly 10 is shown in FIGS. 11-13. Thevalve assembly 10b is similar to the previous embodiment shown in FIGS.1-9, however, the embodiment shown in FIGS. 11-13 includes a collar 48surrounding the middle portion 28 of the body 12. The collar 48 biasesthe middle portion of the central aperture 14 closed, inhibiting gasesand fluids from escaping through the valve assembly 10b. When aninstrument is present in the sealing valve aperture 14, the collar 48forces the middle portion 28 to substantially surround the instrumentand provides longitudinal and radial pressure to discourage any gases orfluids from escaping from the body cavity.

In operation, the splines 32 engage the instrument 44 and substantiallyprotect the valve inner wall 34 as in the previous embodiment describedabove and illustrated in FIGS. 1-9. In the embodiment shown in FIGS.11-13, the collar 48 which biases the middle portion 28 of the body 12closed accommodates the entering instrument 44. The collar 48 urges themiddle portion 28 inwardly to substantially surround the instrument andprovides longitudinal and radial pressure which substantiallydiscourages gases or fluids from escaping from the body cavity duringinsertion, utilization and extraction of the instrument 44 within thevalve assembly 10b. Collar 48 may be constructed of any suitablematerial having resilient elastic properties, e.g., rubber.

Another embodiment of the valve assembly 10c is shown in FIG. 14-15, andis similar to previous embodiments shown in FIGS. 10, and 11-13.However, in the embodiment shown in FIGS. 14-15 the valve assembly 10cincludes a distal end portion 18 which tapers outwardly at an angle 50.The angle 50 is defined by a longitudinal center line 49 and a line 51in accord with the inner wall 34 of the body 12 when middle portion 28is in its closed configuration, i.e., when collar 48 has biased aperture14 closed. The angle is chosen to substantially discourage contact by aninstrument, such as instrument 44a, having a hook 52, as shown in FIG.15 from injuring, e.g., puncturing, or undesirably grabbing the innerwall 34 when the instrument 44a is being removed. The angle 51 istypically about 20° to 60°, preferably 30°.

Another embodiment of the valve assembly 10d is shown in FIG. 16 and issimilar to the previous embodiment shown in FIGS. 14-15. However, theembodiment shown in FIG. 16 has a generally cylindrical shape where theoutside diameter of the valve assembly 10d is substantially constant. Asubstantially solid portion 54 enables the central aperture 14 to taperinwardly from the proximal and distal ends 16, 18 as in previousembodiments. Both the proximal and distal end inner wall 34 may includenubs 46, or splines 32 (not shown), and portion 54 may be further biasedclosed by a collar 48 or a similar biasing means if desired.

Another embodiment of a valve assembly 10 is illustrated in FIGS. 18-19in which the middle portion 28 includes ridges 126 and 127 particularlyplaced to substantially fill a gap 128 which may occur as shown in FIG.17 between the instrument 44 and the inner wall 34 after an instrument44 of a lesser diameter than the unbiased aperture 14 is inserted. Theresilient material of the valve 10 surrounds the instrument 44; however,when accommodating an instrument 44 smaller in diameter than theunbiased aperture 14 at the middle portion 28, the gap 128 forms atleast at one side adjacent to the instrument between the instrument andthe inner wall 34 as shown in FIG. 17. A properly placed ridge or set ofridges 126 or 127 monolithically formed on the inner wall 34substantially fills the gap 128 as shown in FIG. 18.

A plurality of ridges or sets of ridges may be used as in FIG. 19 sothat-the gap 128 resulting from using different sized instruments 44,all of which are smaller in diameter than the unbiased central aperture14, can be eliminated by the properly positioned ridges 126 or 127. Thelocation of the ridge sets 126 and 127, and additional ridges as may bedesired, may correspond to industry standardized instrument diameterssuch as 5 mm, 8 mm, 10 mm, and 12 mm.

More specifically, the ridges 126 may, for example, fill a gap 128 whenan 8 mm diameter instrument is inserted through the valve assembly 10.Similarly, the ridges 127 may, for example, fill a gap 128 when a 5 mmdiameter instrument is inserted through the valve assembly 10.Typically, the ridges or complementary pairs of ridges are axiallyspaced along middle portion 28.

Preferably, the valve assembly 10 is incorporated in a cannula assembly56 of a trocar assembly as best seen in FIG. 20. The valve assembly 10is similar to the previous embodiment shown in FIGS. 14-15. The cannulaassembly 56 includes a valve housing having an upper housing halfsection 60 and a lower housing half section 62, shown separated in FIG.20 for convenience of illustration. The housing half sections 60, 62 arenormally attached along the outer seam by suitable attachment techniquessuch as adhesive, ultrasonic welding, or the like.

The valve or cannula housing includes neck 64 at a distal end having anaperture 65 dimensioned for reception of an appropriate tube such ascannula 66. The cannula 66 is fabricated of a rigid material such as aplastic, fiberglass or metal. The proximal end of the valve housing 68includes a partition 72 for stabilizing the valve assembly 10.

The lower housing half section 62 is shown with the upper housing halfsection 60 removed, so as to illustrate the novel valve assembly 10 ofthe present invention. The valve assembly 10 is shown partially cut awayand in cross section for illustration purposes. Dual reciprocatingsecuring members 74, as seen in FIG. 21, extends across the middleportion 28 of the body 12 as shown. The partition 72 holds the proximalend of the valve assembly 10 in position at plate 24 while the ear 76affixed to middle portion 28 is connected to a corresponding clamp blade80 for stabilizing the middle and distal end portions 28, 18respectively. The partition 72 is constructed of the same relativelyrigid plastic material as the valve housing such as polycarbonate,polyethylene or the like.

The valve assembly 10 includes clamp blades 80 which are connected tothe inner surface of the lower housing half section 62 and the upperhousing half section 60. Each clamp blade 80 is biased in a directiontoward the other by a torsion spring 85 having one leg in engagementwith the adjacent housing wall and the other leg in engagement with apivotal arm 86 pivotally mounted at pivot pins 88. Each pivot arm 86extends as shown, into the path of pins 90, 92 which are slidablymounted within bores 94.

The inner end of each pin 90, 92 communicates with the appropriatepivotal arm 86 such that manually depressing the slidable pins 90, 92toward each other causes the pivot arms 86 to pivotally rotate away fromeach other. This motion causes the clamp blades 80 to separate allowingthe middle portion 28 of the valve assembly 10 to open. When the pins90, 92 are released, the middle portion 28 collapses to theconfiguration shown in FIG. 21 under action of the clamp blades 80 andthe springs which provide a substantially gas tight seal between theproximal end 16 of the valve assembly 10 and the distal end 18. Thesealing effect of the blades 80 on the valve assembly 10 is ofsufficient gas tight character that pressurized gases used to insufflatea body cavity will not pass through the valve 10 when the instrument 44is removed.

The pins 90, 92 may be selectively squeezed as desired by the surgeon toopen the blades 80 to permit entry of the instrument through valveassembly 10, through the cannula 56 and into the body cavity. At thispoint, the tight contact between the instrument 44 and the inner wall 34has sealed the inner body cavity from the outside atmosphere. This sealis provided by the resilient property of the stretched elastomericmaterial at middle portion 28 surrounding the aperture 14. Manipulationof the instrument 44 in any direction will not affect the seal, sincethe elastomeric material defining the aperture 14 will conform to themovements of the instrument and assume a shape necessary to maintaincontact.

The aperture 14 is preferably dimensioned having a diameter between 3and 15 mm to accommodate instruments such as clip appliers, laser tubes,photographic instruments, tubes or the like. However, depending uponneed or application this dimensional range may be varied to accommodateany particular instrument.

Another embodiment of the cannula assembly 56 and valve assembly 10 isshown in FIG. 22, which is similar to the previous embodiment shown inFIG. 21. However in the embodiment shown in FIG. 22 the valve assemblyincludes generally cylindrical pinching members 96. A shaft 97 extendslongitudinally through each member 96 and extends into a groove 98 in aplate 100 connected to the inner surface of the lower housing halfsection 62. The shaft 97 rides freely in the groove and is supported bya support bar 104 attached to the plate 100. A spring 106 positioned inthe groove 98 biases the shaft 97, and thus member 96 to the positionshown at one end of the groove 98. Member 96 biases the middle portion28 of the valve assembly 10 in the closed position substantiallypreventing gases from entering or exiting. Actuation levers 90, 92,positioned in this embodiment perpendicular to levers 90, 92 in FIG. 21,provide manual mechanical activation of members 96 to open valveassembly 10.

In operation, upon insertion of an instrument into the proximal end ofthe valve housing 68 and the proximal end of the valve assembly 10, thenubs 46 engage the instrument providing substantial protection to theinner wall 34. Members 96 are moved in response to actuation of levers90 and 92, and shafts 97 respond by moving in their correspondinggrooves 98. Middle portion 28 of valve assembly 10 provides longitudinaland radial pressure in conjunction with members 96 to the instrument,thus providing and maintaining a substantial gas tight seal.

Another embodiment of the valve assembly and cannula assembly is shownin FIG. 23 and is similar to the previous embodiment shown in FIG. 22.However, in the embodiment shown in FIG. 23 the valve assembly includesa resilient member 108 biased in a generally "U" shaped configurationwhich replaces springs 106. The resilient member 108 is attached to thebottom portion of the shafts 97 and biases shafts 97, and therebymembers 96, in the closed position. The embodiment shown in FIG. 23operates similar to the embodiment shown in FIG. 22.

Another embodiment of the cannula assembly 56 and the valve assembly 10is shown in FIG. 24, and is similar to previous embodiments shown inFIGS. 22 and 23, except for the provision of parallel bars 110 which arepositioned in the lower and upper half sections 62 and 60 of the cannulahousing 56 substantially about the middle portion 28 of the valveassembly 10. The bars 110 are biased towards each other by springs 112attached at their distal ends and aligned in grooves 114. In operation,when an instrument is inserted into the cannula assembly 56 and into thevalve assembly 10 the biased bars 110 move in the grooves 114 againstthe biasing of the springs and maintain a gas tight seal about theinstrument.

Another similar embodiment of the cannula assembly 56 and the valveassembly 10 is shown in FIG. 25. In this embodiment, the valve assembly10 includes a resilient one piece bar 116 having an opening in a middlesegment 118 to accommodate the middle portion 28 of valve assembly 10.The opposite distal ends 120 of the resilient bar 116 are connected tothe side wall receptacles 124. Of course, bar 116 may be constructed oftwo members overlapping each other.

When an instrument is inserted into the cannula assembly 56 and into thevalve assembly 10 the resilient bar 116 accommodates the instrument,while assisting valve assembly 10 in providing longitudinal and radialpressure about the instrument to maintain a fluid tight seal.

When the valve assembly 10 is used as part of a cannula assembly 56 asin the present embodiment of FIGS. 20-25, an obturator of the trocarassembly is fitted within the cannula assembly and used to insert thecannula into a body cavity by first penetrating the cavity wall.Thereafter, the obturator is removed, permitting insertion ofinstruments into the patient's body through the cannula to perform thedesired procedure. Thus, the significance of providing control to thesurgeon over an assuredly sealed cannula valve assembly cannot beover-emphasized. For laparoscopic procedures the valve assembly willprevent leakage of gases to maintain insufflation of the cavity duringthe surgical procedures.

Another embodiment of the valve assembly 10 positioned in a cannulaassembly 56 is shown in FIGS. 26 and 27 and is similar to the previousembodiments shown in FIGS. 21-25. However, in the embodiment shown inFIGS. 26 and 27 the valve assembly 10 preferably includes a pair ofpivotable cams 130 positioned in the lower half section 62 of thecannula housing 56. The cams 130 act as biasing means for biasing themiddle portion 28 of the valve assembly 10 closed prior to instrumentinsertion into the valve assembly 10, and for biasing middle portion 28against the outer surface of an inserted instrument.

Each cam 130 includes a pivot point 132 at a proximal end and anattachment portion 134 for coupling with an actuating spring 136. Thecams 130 further include contact faces 138 and stop surfaces 140. Thecams 130 are positioned on opposite sides of the middle portion 28 andare biased towards one another by the actuation spring 136, thus, thecams 130 work in concert to bias closed the middle portion 28 of thevalve assembly 10 between them.

In operation, prior to instrument insertion in the valve assembly 10,the actuating spring biases the cams 130 towards one another therebybiasing closed the middle portion 28 of the valve assembly 10 andproviding a substantially gas tight seal. After instrument insertioninto the valve assembly 10, the cams 130 pivot at their proximal pivotpoints 132 and rotate distally against the biasing action of theactuation spring 136 assuming the position shown by the dotted lines inFIG. 26. The cams 130 encourage the middle portion 28 of the valveassembly 10 to engage the outer surface of the inserted instrument and,thereby, the valve assembly 10 provides and maintains a substantiallygas tight seal. Lastly, the stop surfaces 140 contact a side wall 142 ofthe lower half section 62 of the cannula housing 56 when the cams 130are fully rotated.

The valve assembly described above in the preferred embodiments andillustrated in the accompanying drawings is preferably capable ofaccommodating instruments varying in diameter of from 3 mm to 15 mm, andpreferably for diameters of from 5 mm to 12 mm. When inserting theinstrument into the valve assembly as described in the above embodimentsand illustrated in the accompanying drawings, the insertion force, i.e.,the axial force asserted against the instrument to pass the instrumentinto and through the valve assembly is preferably kept to a minimum. Forexample, preferable insertion forces of approximately no more than 5pounds are desirable for instruments having approximate diameters ofmore than 9 mm. Insertion forces of approximately no more than 4 poundsare desirable for instruments having approximate diameters of between 5mm and 8 mm.

Moreover, preferable insertion forces of approximately 7 pounds aredesirable for instruments having approximate diameters of 9 mm to 15 mm.Insertion forces of approximately no more than 6 pounds are desirablefor instruments having approximate diameters of between 10 mm and 12 mm.

While the invention has been particularly shown and described withreference to the preferred embodiments, it will be understood by thoseskilled in the art that various modifications and changes in form anddetail may be made therein without departing from the scope and spiritof the invention. Accordingly, modifications such as those suggestedabove, but not limited thereto, are to be considered within the scope ofthe invention.

What is claimed is:
 1. In a cannula subassembly which includes a cannulahousing, a cannula mounted to said cannula housing, and a valve bodymounted within said cannula housing, said valve body defining an openingfor receipt of a surgical instrument, the improvement comprising:aplurality of projecting members monolithically formed on and projectingfrom said valve body surrounding said opening.
 2. A cannula subassemblyaccording to claim 1, wherein said projecting members are selected fromthe group consisting of splines and nubs.
 3. A cannula subassemblyaccording to claim 1, wherein said projecting members are integrallymolded as part of said valve body.
 4. A cannula subassembly according toclaim 1, wherein said projecting members are insert molded and includerigid members therewith.
 5. A cannula subassembly according to claim 4,wherein said rigid members are metallic strips.
 6. A cannula subassemblyaccording to claim 1, wherein said valve body opening is an aperture. 7.A cannula subassembly according to claim 1, further comprising means forautomatically closing said valve body opening.
 8. A cannula subassemblyaccording to claim 7, wherein said automatic closing means is selectedfrom the group consisting of a gel, at least one spring biasing at leastone clamping blade toward said valve body, and a resilient collar.
 9. Acannula subassembly according to claim 1, wherein said projectingmembers are fabricated from a different material than said valve body.10. A cannula subassembly including a cannula housing and a cannulamounted to said housing, said cannula subassembly comprising:a valvebody positioned within said cannula housing formed of a flexiblyresilient material and defining a first substantially round aperture;and at least one ridge member monolithically formed on and protrudingfrom said valve body within said substantially round aperture, whereinsaid ridge member permits said valve body to define a second,substantially round aperture of a lesser cross-section than said firstsubstantially round aperture.
 11. A cannula subassembly including acannula housing and a cannula mounted to said cannula housing,comprising:a valve body formed of a resilient material mounted in saidcannula housing, said valve body tapering from a proximal end having acircular opening of a first diameter to a cylindrical portion defining acircular opening having a second diameter, said first diameter beinggreater than said second diameter, and at least one ridge member on saidvalve body within said cylindrical portion, said ridge member permittingsaid valve body to define a substantially round aperture of a thirddiameter, said third diameter being less than said second diameter. 12.A cannula subassembly according to claim 11, further comprising means tobias said cylindrical portion of said valve body closed, thereby forminga substantially gas tight seal.
 13. A cannula subassembly according toclaim 12, wherein said biasing means includes means to selectively openand close said valve body to permit passage of an instrument throughsaid cylindrical portion.
 14. A cannula subassembly according to claim11, wherein said valve body cortically tapers from said proximal end tosaid cylindrical portion.
 15. A cannula subassembly according to claim11, wherein said valve body tapers from said cylindrical portion to adistal end having a circular opening.
 16. A cannula subassemblyaccording to claim 15, wherein said valve body cortically tapers fromsaid cylindrical portion to said distal end.
 17. A cannula subassemblyaccording to claim 11, wherein said valve body includes a taperedportion between said circular opening of said first diameter and saidsecond circular opening of said second diameter, and further comprisinga plurality of inwardly protruding members on said tapered portion ofsaid valve body, wherein said protruding members guide an element passedthrough said circular opening of said second diameter.
 18. A cannulasubassembly including a cannula housing and a cannula mounted to saidcannula housing, comprising:a valve body formed of a resilient materialmounted in said cannula housing, said valve body defining a taperedportion which tapers from a proximal end having a circular opening of afirst diameter to a cylindrical portion defining a circular openinghaving a second diameter, said first diameter being greater than saidsecond diameter, and a plurality of inwardly protruding members on saidtapered portion of said valve body, wherein said protruding membersguide an element passed through said circular opening of said firstdiameter toward said cylindrical portion.
 19. A cannula subassemblyaccording to claim 18, wherein said inwardly protruding memberssubstantially prevent contact between an element passed through saidcircular opening and said tapered portion.
 20. A cannula subassemblyaccording to claim 18, wherein said inwardly protruding members areselected from the group consisting of splines and nubs.